The method for picking up work pieces includes: storing a representative partial shape, at least one of holding positions in the representative partial shape, and a preference rank for each of the holding positions; obtaining an image information by sensing the work pieces which are accumulated; recognizing exposed portions in the work pieces by performing an edge detection on the image information; selecting at least one of the exposed portions including the representative partial shape as a selected portion; detecting at least one of coinciding portions coinciding with the representative partial shape in the selected portions; determining an optimal holding position from at least one of the holding positions included in the coinciding portion as a determined holding position, based on the preference rank; and transmitting a holding command to hold the determined holding position.